91 K1500 surge

[Chevy Guy]

Hi guys, I have been building a 91 K1500 ex cab. It has the 350 with a 5 speed. Vin K. Anyway, If I give it just a hair of gas it has a the RPM's surge up and down. Happens when I give it about a 1/4 of gas pedal. I thought it may be the TPS so I changed it but it is still there. Other than that, all runs good. It does have 192k. So far I have only replaced the regular service stuff. Air filter, fuel filter, plugs, cap and rotor, PCV valve. The injector stream looks to be ok. Any thoughts on this one?

 

[Texan]

First question. Have you done the jumper wire thing to check for the flashing light
code checking for the OBD system? If I remember correctly, this engine has a TBI
system with a IAC valve that can get carbon built up inside. How about a vacuum
leak somewhere?

 

[Chevy Guy]

First question. Have you done the jumper wire thing to check for the flashing light
code checking for the OBD system? If I remember correctly, this engine has a TBI
system with a IAC valve that can get carbon built up inside. How about a vacuum
leak somewhere?

No codes. I have an OBD 1 reader. No vacuum leaks that I can find. I thought the IAC would only effect the engine at idle. I'll remove it and clean it anyway, couldn't hurt right?

 

[Texan]

No codes. I have an OBD 1 reader. No vacuum leaks that I can find. I thought the IAC would only effect the engine at idle. I'll remove it and clean it anyway, couldn't hurt right?

Boy you are bringing back some old memories. Have you checked the fuel pressure? The reason I ask, is because I remember
thinking the TBI FI stream looked OK, but I found out that looks can be deceiving. Yes you can remove the IAC valve, but handle
carefully, because it has a pintle that is adjustable. See if you can find a discussion about how it works.

 

[gmcman]

Have you changed the fuel filter?